Fitting procedure for hearing devices and corresponding hearing device

ABSTRACT

The method for adjusting a hearing device ( 11 ) to the hearing preferences of a user of the hearing device comprises
         a) adjusting at least one of N parameters (P1, P2), preferably with 2≦N≦4;   b) obtaining a gain model (G), which is identical with the output of a fitting rationale (F) applied to a model audiogram (A), wherein the model audiogram depends on the N parameters and is independent of possibly existing audiogram values measured for the user; and   c) using the gain model (G) or a gain model derived therefrom in said hearing device ( 11 ).
 
Preferably, the model audiogram (A) is an approximation to an audiogram occurring in a pre-defined empirical sample of individual audiograms. The user preferably carries out the method by himself and without external equipment. A corresponding arrangement ( 1 ) is disclosed, too. A simple and efficient hearing device fitting can be achieved.

TECHNICAL FIELD

The invention relates to the field of hearing devices and in particularto the fitting of hearing devices, i.e., to adjusting a hearing deviceto the hearing preferences of a user of said hearing device. It relatesto methods, apparatuses and computer program products according to theopening clauses of the claims.

Under a hearing device, a device is understood, which is worn in oradjacent to an individual's ear with the object to improve theindividual's acoustical perception. Such improvement may also be barringacoustic signals from being perceived in the sense of hearing protectionfor the individual. If the hearing device is tailored so as to improvethe perception of a hearing impaired individual towards hearingperception of a “standard” individual, then we speak of a hearing-aiddevice. With respect to the application area, a hearing device may beapplied behind the ear, in the ear, completely in the ear canal or maybe implanted.

A hearing system comprises at least one hearing device. In case that ahearing system comprises at least one additional device, all devices ofthe hearing system are operationally connectable within the hearingsystem. Typically, said additional devices such as another hearingdevice, a remote control or a remote microphone, are meant to be worn orcarried by said individual.

BACKGROUND OF THE INVENTION

The most common way of fitting a hearing device, i.e., adjusting ahearing device to the preferences of a user of said hearing device,involves using a personal computer external to the hearing device andfurther equipment for measuring an audiogram of said user andcalculating, on basis of the audiogram, a gain model to be used for thisuser, wherein a gain model represents the basic amplificationcharacteristic in dependence of input level and frequency. This gainmodel is used at least as a first fit. Typically, later, somefine-tuning will take place, based upon said gain model, so as tofurther improve the gain model for improving the user's hearingsensation.

Said audiogram is unique for each user, and obtaining it involves inmany cases a precise determination of the user's hearing loss for manyfrequencies. The whole procedure of measuring the audiogram is carriedout by a hearing device professional such as an audiologist.

The determination of the gain model is carried out using a specificalgorithm, also referred to as fitting algorithm or fitting rationale,such as NAL-NL1, DSL-i/o and Phonak Digital. After all requiredaudiogram data are taken and entered, the corresponding calculation isstarted.

When the gain model is finally determined, it will be transmitted to thehearing device. Possibly after another command, the transmitted gainmodel (typically represented by several data, in particular parametersettings) will be used in the hearing device, and the hearing deviceuser finally can experience the perception of environmental sound whenthe newly obtained gain model is working.

From EP 1 617 705 A2, a hearing device is known, which can be fittedin-situ by the hearing device user. The hearing device plays test soundsto the user, which are known to the user from everyday life, and theuser uses the hearing device's volume wheel for adjusting each testsound to comfortable audibility. Having made such adjustments forseveral test sounds, new parameter settings are calculated and used.

From U.S. Pat. No. 4,947,432, a hearing system comprising a hearing-aiddevice and a remote control is known, wherein it is provided that theremote control transmits data to the hearing-aid device, which—whenreceived in the hearing-aid device—are used for adjusting thetransmission characteristics of the hearing device.

From U.S. Pat. No. 6,175,635 B1, it is known to use one user control ofa hearing device for simultaneously setting severalaudiological/acoustical parameters of a signal processor of the hearingdevice.

From U.S. Pat. No. 5,202,927, it is known to adjust the transmissioncharacteristic between microphone and earphone of a hearing device bymeasuring an audiogram of the hearing device user and inputtingone-by-one the so-obtained audiometric data into a remote control of thehearing device. The audiometric data can relate to the hearing deviceuser's hearing loss at different discrete frequencies. When the wholeaudiogram, i.e. all said audiometric data, is entered into the remotecontrol, the data are transmitted to the hearing device. In the hearingdevice, the data are used for adjusting the processing.

From U.S. Pat. No. 5,303,306, a method for configuring a hearing-aiddevice is known, in which an audiologist performs conventionalaudiometry by gathering audiogram data, e.g., a standard pure tone airconduction audiogram. From the so-obtained audiogram, the audiologistdetermines manually, using pre-defined overlays, two valuescharacterizing the audiogram: a value describing the curve shape of theaudiogram and a value the magnitude of hearing loss of the user. Thesetwo values are entered into a remote control of the hearing-aid deviceby setting dip switches. In the remote control, the dip switch settingsare used to generate baseline settings for the hearing device circuitry.

It is desirable to provide for an alternative way of fitting a hearingdevice.

SUMMARY OF THE INVENTION

Therefore, one object of the invention is to create an alternative wayof adjusting a hearing device to the hearing preferences of a user ofsaid hearing device. In particular, a method for adjusting a hearingdevice to the hearing preferences of a user of said hearing device, anda corresponding hearing system, and a corresponding computer programproduct shall be provided.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which can easily becarried out by said user himself, in particular without or substantiallywithout the help of a professional hearing device fitter.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which can becarried out solely with the hearing device or with the hearing system towhich the hearing device belongs, without the need of additional means.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which is simple tocarry out and does not require a particular expertise.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which is easilyimplementable.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which can becarried out even if no personal computer or special, in particularaudiological equipment is available.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which does notrequire the generation of special test sounds.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which can becarried out within a relatively short period of time.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which needs littlestorage space in the hearing device or hearing system.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which needs littleprocessing power in the hearing device or hearing system.

Another object of the invention is to provide for a way of adjusting ahearing device to the hearing preferences of a user, which can beaccomplished without measuring an audiogram for the user.

Further objects emerge from the description and embodiments below.

At least one of these objects is at least partially achieved byapparatuses and methods according to the patent claims.

The method for adjusting a hearing device to the hearing preferences ofa user of said hearing device comprises the steps of

a) adjusting at least one of N parameters;

b) obtaining a gain model, which is identical with the output of afitting rationale applied to a model audiogram, wherein said modelaudiogram depends on said N parameters and is independent of possiblyexisting audiogram values measured for said user.

The arrangement for adjusting a hearing device to the hearingpreferences of a user of said hearing device comprises

said hearing device;

at least one user control for adjusting N parameters;

a control unit adapted to obtaining a gain model usable in said hearingdevice, which is identical with the output of a fitting rationaleapplied to a model audiogram, wherein said model audiogram depends onsaid N parameters and is independent of possibly existing audiogramvalues measured for said user.

The computer program product for adjusting a hearing device to thehearing preferences of a user of said hearing device comprises programcode for causing a computer to perform the steps of

A) receiving user input indicative of a requested adjustment of Nparameters;

B) obtaining a gain model, which is identical with the output of afitting rationale applied to a model audiogram, wherein said modelaudiogram depends on said N parameters and is independent of possiblyexisting audiogram values measured for said user.

Through this, an efficient way of fitting a hearing device can beprovided.

The expression “possibly existing audiogram values measured for saiduser” means that there may exist audiogram values that have beenmeasured for said user, but as well it is possible that there may neverhave been carried out any audiogram value measurements for said user.I.e., independent of there existing any audiogram values measured forsaid user or not: even if audiogram values measured for said user exist,said model audiogram will be independent of those. Accordingly, forobtaining said model audiogram, it is not required to measure audiogramvalues for said user.

Typically, at least two of the N parameters are continuous orquasi-continuos parameters. In case of quasi-continuos parameters, eachparameter typically can assume one of at least 10 or 20 or 30 possibledifferent values and up to 100 or 80 or 60 possible different values.

Typically, step b) is carried out in dependence of said N parameters.

Usually, each of said N parameters is different from an audiogramparameter.

Audiogram values are, e.g., hearing threshold values, most comfortablelevels (MCL) or other audiological values contributing to an audiogramof a specific user.

Usually, step b) is carried out independently of possibly existingaudiogram values measured for said user.

The inventor recognized the great value that is contained in fittingrationales. And the inventor furthermore found out that a reasonablefirst fit of a hearing device can be achieved based on an audiogramwhich does not fully but only approximately agree with an audiogrammeasured for the individual user of the hearing device.

Said adjusting of a parameter can also be termed selecting a setting ofthe parameter, i.e. selecting a parameter setting.

By means of adjusting said N parameters, a gain model can be determined,which is at least approximately identical with a gain model that can beobtained by applying a certain fitting rationale to a model audiogram.When a reasonable fit of the hearing device, more precisely: of the gainmodel used in the hearing device of the user, is achieved, it is likelythat said model audiogram approximately corresponds to an audiogram,which would be measured for said user.

It shall be pointed out that gain models are typically represented inform of data representative of a gain model, such as parameters for asignal processor. Therefore, the term “gain model” may occasionally beused, when, more strictly spoken, “data representative of a/the/saidgain model” is meant. A similar remark applies to audiograms and fittingrationales mentioned in this application.

In one embodiment, step b) is carried out automatically after step a).Preferably, there is no unnecessary time delay before starting step b),maybe even no extra button pressing or another action initiating step b)besides adjusting at least one of said N parameters.

Preferably, it takes at most 4 seconds, preferably at most 2 seconds,more preferably at most 1 second after step a) is finished, before stepb) is finished.

In one embodiment, the method comprises the step of

c) using said gain model or a gain model derived therefrom in saidhearing device.

Preferably, there is no unnecessary time delay before starting step c)after step b) is finished.

In one embodiment, step c) is carried out automatically after step b)

These embodiments can contribute to enabling the method to be carriedout in real-time; i.e. with only little delay and/or no further actionsafter carrying out an adjustment of at least one of said N parameters,the user will be able to perceive sound processed using thenewly-obtained gain model.

Preferably, the time span between finishing step a) and starting step c)is 3 seconds or less, in particular 1.5 seconds or less.

In one embodiment, 2≦N≦4 applies. The inventor found that one parameterwill usually not be sufficient for achieving in a simple way a good fitfor most users. The inventor furthermore found that five or moreparameters will usually tend to make the method too complicated forusers. Even four parameters can, for several users, be too much to copewith. Three parameters can usually be handled by many users, and goodfitting results can be achieved. Nevertheless, it has been found thatnot only is the handling of only two parameters particularly easy, butalso the definition of the two parameters can be accomplished in such away, that for most users, a well-suiting gain model can be selected.

In one embodiment, said model audiogram is an approximation to anaudiogram occurring in a pre-defined empirical sample of individualaudiograms. Empirical samples of individual audiograms are available,e.g., from universities or hospitals. Such empirical samples ofindividual audiograms comprise typically at least 1000, at least 5000 orat least 12000 or even more audiograms of individuals. It is possible tofind a set of parametrized functions, which provide a reasonable fit tomost of the audiograms in the empirical sample. I.e. by means of suchparametrized functions, most of said audiograms in the empirical sampleare well-approximated, wherein the choice of parameters determinesexactly what each function looks like. These functions are the modelaudiograms referred to before and later on. Each model audiogram isaccessible by a certain setting of the parameters. The number ofparameters can be chosen when searching the set of parametrizedfunctions.

In one embodiment, a definition of at least one, in particular of eachof said N parameters is derived based upon a statistical analysis ofsaid pre-defined empirical sample of individual audiograms. Such astatistical analysis may comprise factor analysis or other means andalgorithms.

Note that it is stated in the description of this embodiment, that thedefinition of the parameters is derived based upon a statisticalanalysis, which shall not be confused with the parameter setting (value)resulting from the parameter adjustment in step a). The definitions ofthe parameters describe, how a model audiogram is obtained in dependenceof said parameter.

In one embodiment, step b) comprises the steps of

b1) obtaining said model audiogram;

b2) applying said fitting rationale to said model audiogram.

This is one way of carrying out step b). As an intermediate result, saidmodel audiogram is obtained, e.g., as a set of typically 10 to 20hearing loss values or most-comfortable levels; and then, a selectableor typically prescribed fitting rationale is applied to the modelaudiogram, so as to obtain the sought gain model.

Step b1) can be considered a carrying-out of a certain algorithm orprescribed calculation or function in dependence of the settings of theN parameters. Step b2) can be considered a carrying-out of a certainalgorithm or prescribed calculation or function in dependence of themodel audiogram. The fitting rationale can, e.g., be provided as afunction, numerically, or as a look-up table.

Using a look-up table has the great advantage that steps b) and b2) canbe carried out particularly fast.

In one embodiment, step b) comprises the step of

b3) obtaining data from a look-up table.

Not only the fitting rationale can be provided in form of a look-uptable, but it is also possible to obtain the model audiogram from alook-up table, in dependence of the N parameters. And it is alsopossible to provide all possible gain models as look-up tables.

In one embodiment, step a) is carried out by said user.

In one embodiment, the method is carried out using solely devices of ahearing system to which said hearing device belongs. This makesadditional equipment superfluous.

In one embodiment, the arrangement is comprised in a hearing systemcomprising said hearing device.

In one embodiment, the arrangement is comprised in said hearing device.

In one embodiment, there is at least one user control provided for eachof the N parameters.

In one embodiment of the computer program product, said computer iscomprised in a hearing system comprising said hearing device.

Further embodiments of arrangements and of computer program productscorrespond to embodiments of methods according to the invention.

The advantages of the arrangements and computer program productscorrespond to the advantages of corresponding methods.

Further preferred embodiments and advantages emerge from the descriptionand the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention is described in more detail by means of examplesand the included drawings. The figures show:

FIG. 1 a block diagram illustrating a method according to the invention;

FIG. 2 a schematic illustration of an arrangement according to theinvention, in particular in a hearing device;

FIG. 3 a block diagram illustrating how suitable parameters and modelaudiograms can be found.

The reference symbols used in the figures and their meaning aresummarized in the list of reference symbols. The described embodimentsare meant as examples and shall not confine the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a block diagram illustrating a method according to theinvention, i.e. of a method for adjusting a hearing device to thehearing preferences of a user of said hearing device. In step 100, thefitting of the hearing device is started. In step 110, the user selectssettings for at least one parameter, typically by manipulating a usercontrol of the hearing device or of a remote control belonging to thehearing device. In steps 120 and 130, a gain model is obtained independence of the selected parameter settings. E.g., first, a modelaudiogram is obtained in dependence of the selected parameter settings(step 120), and then, a fitting rationale, e.g., Phonak Digital orNAL-NL1, is applied to the model audiogram, so as to obtain a gain model(step 130).

The so-obtained gain model is then applied to the hearing device (step140), so that the user can perceive sound processed using the gain model(step 150). For this, sounds from the surroundings (environmentalsounds) can be used, but it is also possible to use test sounds, e.g.,generated within the hearing device or within a hearing systemcomprising the hearing device.

If the user is content with how he perceives sound (step 160), i.e.content with the new gain model, the fitting procedure is or can befinished (step 170). If the is not content, it can be continued withstep 110, i.e., the user will select at least one new parameter setting.

FIG. 2 is a schematic illustration of an arrangement 1 according to theinvention. The arrangement can be identical with a hearing system 10comprising the hearing device 1 and can be identical with the hearingdevice 1.

The arrangement 1 comprises an input unit 20, e.g., a microphone, asignal processing unit 30 for processing audio signals received from theinput unit 20, and an output unit, e.g., a loudspeaker, for providingthe user with signals to be perceived by the user, typically soundwaves.

The arrangement 1 furthermore comprises a user interface 50 operatableby the user and comprising several, e.g., two, user controls 51,52 suchas toggles or sliders, a control unit 50, a storage unit 70 comprisingdata describing model audiograms and a storage unit 80 comprising datadescribing at least one fitting rationale.

The arrangement 1 can be used for carrying out a method as illustratedin FIG. 1, in the following way: The user wants to adjust the hearingdevice 1 to his hearing preferences, i.e. adjust the hearing device'stransfer function, which is basically done by amending the gain model 31realized in the signal processor 30. For this, the user manipulates usercontrols 51 and/or 52, which results in parameter settings P for twoparameters P1 and P2 to which the user control 51 and 52, respectively,are assigned.

The parameters P1 and P2 can, e.g., be chosen (defined) such thatadjusting P1 primarily is perceived as adjusting a gain or an overallvolume, whereas adjustments of P2 would primarily result in timbrechanges for signals perceived by the user. For example, when consideringan audiogram of hearing loss values, the model audiograms—conventionallyrepresented by a curve (actually several discrete points describing acurve) with the frequency on the x-axis and the hearing loss on they-axis (with stronger hearing loss values below lighter hearing lossvalues)—could be comprised of an approximately horizontal approximatelystraight line for low frequencies up to a treshold frequency and, forfrequencies above said treshold frequency, of an approximately straightor curved line with negative slope. Changing P1 could in this casebasically shift the model audiogram parallel to the y-axis, whereaschanging P2 could change said treshold frequency and/or said negativeslope (more precisely its steepness and/or its shape).

The settings P of the parameters P1, P2 are passed on to the controlunit 60, which uses them for obtaining in dependence thereof a modelaudiogram A (more precisely: data describing or representative of amodel audiogram A) from storage unit 70. The audiogram may berepresented by or comprise, e.g., ten to twenty values indicating ahearing loss or a most comfortable level for different frequencies.

Control unit 60 obtains data describing a fitting rationale from storageunit 80 and applies the fitting rationale to the audiogram A, so as toobtain a gain model G. The new gain model G or a gain model derivedtherefrom is then used in signal processing unit 30, and the user willperceive sound differently. Depending on whether parameter P1 or P2 hasbeen changed more pronouncedly, the user will perceive sound morestrongly changed in volume or more strongly changed in timbre (tonalbalance), if the parameters P1, P2 are defined in the before-mentionedway.

Preferably, manipulations of the user interface will result inperceivable changes in the gain model 31 nearly immediately, preferablyno more than 2 seconds or 1 second after a manipulation. Storing modelaudiograms and/or fitting rationales in form of, e.g., look-up tables,can help to reduce the time between a user interface manipulation andthe onset of the use of a corresponding new gain model.

It is readily understood that the constituents of the arrangement shownin FIG. 2 are at least in part merely functional units, which of coursecan be arranged in various ways, e.g., two or more of them can be unitedin one physical unit, or one or more of them can be distributed over twoor more physical units. As it is common today, many of these functionsare realized in form of software anyway, which renders differentiationsother than a functional differentiation little meaningful.

If the user interface 50 is comprised in a device of a hearing system 10other than the hearing device 11, e.g., in a remote control, data wouldhave to be transmitted, preferably in a wireless fashion, from theremote control to the hearing device 1. In order to save storage spaceand computing power in the hearing device 11, it could be advisable tocomprise also control unit 60 and storage units 70 and 80 in the remotecontrol, thus transmitting the gain model G from the remote control tothe hearing device 11.

FIG. 3 is a block diagram illustrating an example of how suitableparameters and model audiograms can be found. It starts with anempirical sample of individual audiograms, comprising typically some10000 audiograms of different individuals (step 200). That empiricalsample can be analyzed, so as to find a parametrized form of audiograms,which are reasonable approximations of most of the audiograms in theempirical sample (step 210). Statistical methods and/or (mathematical)fitting software can be used to accomplish this. The number N ofparameters can be pre-defined or result from the analysis of theempirical sample.

For example, it is possible to find a suitable parametrized form of(model) audiograms by trying to minimize the deviation between eachaudiogram in the empirical sample and the best-suiting model audiogram,e.g., by minimizing the following expression:

Σ(Ai−Am)²

wherein Σ designates the sum over all audiograms Ai in the empiricalsample, and Am is the best-suiting model audiogram for an audiogram Aiof the empirical sample.

It is also possible to use all the audiograms of the empirical sample asmodel audiograms, so that by varying the N parameters, a certainaudiogram Ai of the empirical sample is selected from which a gain modelis obtained by application of a fitting rationale. Or a specificselection of audiograms of the empirical sample can be used as modelaudiograms, e.g., audiograms that are typical for particularly manyaudiograms in the empirical sample.

It is, of course, possible to choose gain models directly by adjustingparameters P1, P2, i.e. without the intermediate step of actuallyobtaining an audiogram. In that case, gain models, which could beobtained by applying a fitting rationale to a model audiogram, wouldhave to be available in a parametrized form depending on P1 and P2.

The invention makes it possible that a hearing device user selects oneof a multitude of parametrized audiograms (model audiograms) byadjusting N parameters, e.g., by using user controls of the user'shearing system; and thereupon, the hearing device will use a gain modelwhich is or at least can be obtained by applying a (fixed or selectable)fitting rationale to the selected model audiogram.

The invention can be used in real life situations and by the userhimself without external help and without using devices external to thehearing system, such as a suitable computer plus software and calibratedaudiologic equipment. No audiogram data have to be obtained from theuser (no audiogram measurements). Not all (potential) hearing deviceusers have access to a hearing device professional or the correspondingexpertise, which are not everywhere available, so it is valuable toprovide a fitting process that can be handled by the user, not requiringany specific knowledge.

LIST OF REFERENCE SYMBOLS

1 arrangement

10 hearing system

11 hearing device, hearing-aid device

20 input unit, acoustic-electric converter unit, microphone arrangement

30 signal processing unit, digital signal processor

31 currently used gain model, parameter storage

40 output unit, electric-acoustic converter unit, loudspeaker

50 user interface

51 user control, toggle

52 user control, toggle

60 control unit, controller

70 storage unit

80 storage unit

100 . . . 220 steps

A audiogram, data representative of audiogram

F fitting rationale, data representative of fitting rationale

G gain model, data representative of gain model

P parameter settings, values assigned to parameters

1. A method for adjusting a hearing device to the hearing preferences ofa user of said hearing device, said method comprising the steps of a)adjusting at least one of N parameters; b) obtaining a gain model, whichis identical with the output of a fitting rationale applied to a modelaudiogram, wherein said model audiogram depends on said N parameters andis independent of possibly existing audiogram values measured for saiduser.
 2. The method according to claim 1, wherein step b) is carried outautomatically after step a).
 3. The method according to claim 1,comprising the step of c) using said gain model or a gain model derivedtherefrom in said hearing device.
 4. The method according to claim 3,wherein step c) is carried out automatically after step b).
 5. Themethod according to one of the preceding claims, wherein 2≦N≦4.
 6. Themethod according to claim 1, wherein said model audiogram is anapproximation to an audiogram occurring in a pre-defined empiricalsample of individual audiograms.
 7. The method according to claim 6,wherein a definition of at least one of said N parameters is derivedbased upon a statistical analysis of said pre-defined empirical sampleof individual audiograms.
 8. The method according to claim 1, whereinstep b) comprises the steps of b1) obtaining said model audiogram; b2)applying said fitting rationale to said model audiogram.
 9. The methodaccording to claim 1, wherein step b) comprises the step of b3)obtaining data from a look-up table.
 10. The method according to claim1, wherein step a) is carried out by said user.
 11. The method accordingto claim 1, which is carried out using solely devices of a hearingsystem to which said hearing device belongs.
 12. An arrangement foradjusting a hearing device to the hearing preferences of a user of saidhearing device, comprising said hearing device; at least one usercontrol for adjusting N parameters; a control unit adapted to obtaininga gain model usable in said hearing device, which is identical with theoutput of a fitting rationale applied to a model audiogram, wherein saidmodel audiogram depends on said N parameters and is independent ofpossibly existing audiogram values measured for said user.
 13. Thearrangement according to claim 12, which is comprised in a hearingsystem comprising said hearing device.
 14. The arrangement according toclaim 12, which is comprised in said hearing device.
 15. Computerprogram product for adjusting a hearing device to the hearingpreferences of a user of said hearing device, comprising program codefor causing a computer to perform the steps of A) receiving user inputindicative of a requested adjustment of N parameters; B) obtaining again model, which is identical with the output of a fitting rationaleapplied to a model audiogram, wherein said model audiogram depends onsaid N parameters and is independent of possibly existing audiogramvalues measured for said user.
 16. The computer program productaccording to claim 15, wherein said computer is comprised in a hearingsystem comprising said hearing device.